A spokesman for the force said officers had travelled to Hampstead to carry out the searches earlier this week as part of a probe into historic child sex offences alleged to have taken place in the Leicestershire area.

No arrests have been made as part of the investigation and no one has been interviewed by police.

Lord Janner, a former Labour MP representing Leicester North West and then Leicester West for 27 years, was made a life peer on his retirement from parliament in 1997 as Baron Janner of Braunstone, in Leicestershire.

The father-of-three, whose wife of more than 40 years died in 1996, became a barrister in 1954 and was appointed a QC in 1971.

He is associated with a number of Jewish organisations having served as president of the Board of Deputies of British Jews from 1978 to 1984.

He chairs the Holocaust Educational Trust and is vice president of the World Jewish Congress.

Lord Janner is described on his website as “a key international figure in efforts to seek compensation and restitution for Holocaust victims”.